SAMHD1 Promotes DNA End Resection to Facilitate DNA Repair by Homologous Recombination

Publication date: 22 August 2017
Source:Cell Reports, Volume 20, Issue 8
Author(s): Waaqo Daddacha, Allyson E. Koyen, Amanda J. Bastien, PamelaSara E. Head, Vishal R. Dhere, Geraldine N. Nabeta, Erin C. Connolly, Erica Werner, Matthew Z. Madden, Michele B. Daly, Elizabeth V. Minten, Donna R. Whelan, Ashley J. Schlafstein, Hui Zhang, Roopesh Anand, Christine Doronio, Allison E. Withers, Caitlin Shepard, Ranjini K. Sundaram, Xingming Deng, William S. Dynan, Ya Wang, Ranjit S. Bindra, Petr Cejka, Eli Rothenberg, Paul W. Doetsch, Baek Kim, David S. Yu
DNA double-strand break (DSB) repair by homologous recombination (HR) is initiated by CtIP/MRN-mediated DNA end resection to maintain genome integrity. SAMHD1 is a dNTP triphosphohydrolase, which restricts HIV-1 infection, and mutations are associated with Aicardi-Goutières syndrome and cancer. We show that SAMHD1 has a dNTPase-independent function in promoting DNA end resection to facilitate DSB repair by HR. SAMHD1 deficiency or Vpx-mediated degradation causes hypersensitivity to DSB-inducing agents, and SAMHD1 is recruited to DSBs. SAMHD1 complexes with CtIP via a conserved C-terminal domain and recruits CtIP to DSBs to facilitate end resection and HR. Significantly, a cancer-associated mutant with impaired CtIP interaction, but not dNTPase-inactive SAMHD1, fails to rescue the end resection impairment of SAMHD1 depletion. Our findings define a dNTPase-independent function for SAMHD1 in HR-mediated DSB repair by facilitating CtIP accrual to promote DNA end resection, providing insight into how SAMHD1 promotes genome integrity.

Graphical abstract

Teaser

SAMHD1 is a dNTP triphosphohydrolase, which restricts HIV-1 infection and is dysregulated in Aicardi-Goutières syndrome and cancer. Daddacha et al. define a dNTPase-independent function for SAMHD1 in HR-mediated DSB repair by facilitating CtIP accrual to promote DNA end resection, providing insight into how SAMHD1 promotes genome integrity.


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